This application claims priority from British patent application serial no. 0027190.8 filed Nov. 7, 2000.
The present invention relates to valve assemblies.
It is an object of the present invention to provide a valve assembly which operates within a fluid cooling system for, for example a vacuum pump to reduce the fluid flow when not required and to open when full flow is needed.
According to the present invention, a valve assembly comprises a housing having an inlet and spaced therefrom an outlet, means located in the housing for controlling the flow of fluid between the inlet and the outlet, said means including a main valve movable between a first relatively closed position and a second open position, said movement being controlled by a pilot valve assembly including a temperature sensitive member such that when the temperature of the fluid reaches a predetermined value the pilot valve is opened thereby allowing the main valve to move from said first to the second position.
Preferably, the heat sensitive member is in the form of one or more bimetallic discs which when subjected to a temperature above a predetermined value will cause the pilot valve to open thereby allowing the main valve to move from its first to its second position.
In one embodiment the main valve has formed therein at least one notch which allows the passage of fluid from the inlet towards the outlet when the main valve is in the first relatively closed position.